[Illustration: SIEMENS' GAS PRODUCER AND GAS MOTOR. Fig 2.]
Fig. 2 is a vertical section of a gas producer and scrubber, which, as stated above, may be employed in combination with engines such as have been described for supplying them with combustible gas. The producer is a vessel lined with refractory material. At the top it has a supply opening covered by a cap, U, having a flange dipping into a sand joint. At the bottom it has an opening surrounded by inclined bars, V, which rest upon a water-pipe perforated with small holes, by which water issues to cool the bars and generate vapor. This vapor rises along with a limited supply of air through the incandescent fuel above, and combustible gas is produced, which collects in the annular space, and is led thence by a pipe to the scrubber. The scrubber is a vessel containing in its lower part water, W, supplied by a pipe, and having an overflow. By means of a perforated deflecting plate the gas is caused to bubble through the water, whereby it is cleansed and cooled, and it passes by a pipe, X, to supply the engine. The upper end of the vertical pipe of the scrubber is made open and covered by a cap sealed in water while the producer is at work. In starting the producer this cap is removed and a chimney pipe put in its place, so as to give a draught for kindling the fuel in the producer. When the fuel is kindled the chimney is removed and the cap substituted, whereupon the suction of the engine continues the draught as required.
This paper, lately read before the Institution of Mechanical Engineers, London, is a description of the construction and working of a dredger on M. Bazin's system, as used by the author for the past three years in dredging sand and other material in Lowestoft Harbor. The dredger is represented in its general features on next page, Fig. 1. The total length of the hull is 60 ft., with 20 ft. beam. In the after part of the hold is placed a horizontal boiler, A, which supplies steam to a pair of inverted vertical engines, B. These engines drive, through belts and overhead pulleys, a centrifugal pump, C, which discharges into the open trough, H. The suction pipe, D, of this pump passes through the side of the dredger, and then forms an elbow bent downward at an angle of 45 deg. To this elbow is attached a flexible pipe, E, 12 in. in diameter and 25 ft. long, made of India-rubber, with a coil of iron inside to help it to keep its shape. At the lower end of this pipe is an elbow-shaped copper nozzle which rests on the bottom, and is fitted with a grating to prevent stones getting into the pump and stopping the work. The flexible tube is supported by chains that pass over the head of a derrick, F, mounted at the stern of the dredger, and then round the barrel of a steam winch. By this means the depth of the nozzle is altered, as required to suit the depth of water.